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6.2 Value added analyses and visualization tools

6.2.1 Climate Observations and Reanalysis

An important component of climate services is the development of
visualization and analysis tools for the immediate synthesis and
diagnosis of large operational climate datasets in near real time. CDC
maintains a large and diverse collection of climate datasets in
support of in-house research, which are also publicly
available. Providing value-added access to high-quality, long-term
records of observations is increasingly important to meaningfully
evaluate climate system change, and to place such change in the
context of natural variability. Outside users can download these data
for further analysis; however, the amount of data available is often
extremely large and not readily accessible without significant
effort. CDC thus also provides a number of visualization and analysis
tools that allow users to "test" out the data before going through the
process of downloading. CDC's in-house scientific expertise provides
insights into the types of questions climate researchers are
investigating and the preferred WWW display and analysis tools to
address these questions. A diverse number of visualization and
analysis tools are available through the CDC Interactive Plotting and
Analysis Pages (http://www.esrl.noaa.gov/psd/PublicData/web_tools.html). A
subset of these visualization and analysis tools plot data, or
averages of data, over different times, allow users to specify the
region, variable, type of plot (mean, anomaly, long-term mean, or
time-by-latitude plots for example) and various other
parameters. User-specified averaging over different intervals can be
applied to study the average effects of phenomena such as ENSO (e.g.,
Fig. 6.6), or to examine possible decadal
climate changes. On shorter time scales, users can systematically
analyze synoptic variability or examine the current weather/climate in
greater detail by using a choice of the monthly mean compositing page,
the daily compositing page, the US climate division dataset plotting
page, the time section plotting page, the operational data plotting
page, and the chi-corrected heating atlas. CDC also provides more
sophisticated analysis tools such as a monthly correlation page, the
US climate division correlation page, and a wavelet analysis page.

Fig. 6.6 WWW-based graphic generated using the
correlation analysis tools to evaluate the relationship between NCEP
Reanalysis precipitation and the SOI.

The correlation/regression analysis tools allow users to test (linear)
relationships among the data and a suite of common indices of
atmospheric or ocean variability (e.g., ENSO, PNA, or the AO), or a
user-specified time series. The wavelet analysis tool allows users to
examine the variability of some common atmospheric or user-provided
time series. CDC also provides a WWW-based experimental climate
services product that estimates the relative risks of extreme
precipitation and temperature anomalies in relation to ENSO (e.g., the
regional increased risk of extreme warm/cold or dry/wet, Fig. 6.7, http://www.esrl.noaa.gov/psd/Climaterisks/).

Fig. 6.7 Increased risks of precipitation
extremes for Jan.-Mar La Niña conditions based on the SOI for
1896-1995. Relative risks at the 1.75x and 2.00x levels of either dry
or wet extremes are significant at the 93.6% and 98.2% levels,
respectively.

All of these WWW tools are used extensively for research, for
educational purposes by teachers, and to assess current or possible
future weather and climate conditions by both public and private
sector decision makers (e.g., energy companies, water managers). In
addition, the plots and analyses generated by these pages have been
presented at a wide variety of scientific meetings and have been
incorporated in books and journal articles by both CDC and non-CDC
scientists. The ideas generated by users able to quickly explore the
data have made the CDC WWW-based visualization and analysis tools
extremely useful and have saved much time and energy for researchers
both outside and inside CDC.

6.2.2 Climate Model Output

CDC has begun assembling large ensembles of climate model simulations
of the 20th Century, many of which have been performed at other
institutions, and making these data accessible to the research
community for evaluation and intercomparisons. As part of this effort,
CDC has developed a parallel set of WWW-based visualization and
analysis tools to intercompare GCM simulations of climate, explore
causal mechanisms for change in long-term observed records, and to
establish the fidelity of model simulated climate. These WWW-based
tools allow considerable user interaction and manipulation of the data
using CDC computing platforms. GFDL R30 resolution model climate
simulations are currently available and may be intercompared with
re-analysis climatologies (http://www.esrl.noaa.gov/psd/gfdl). The
GFDL data will be augmented to include AMIP-style simulations for
1950-1999, and runs using idealized SSTs. Also available on-line is
the NCAR CCM3 AMIP climate model simulations spanning 1950-1999 with
globally prescribed and tropically prescribed SSTs (http://www.esrl.noaa.gov/psd/Composites/CCM). In
addition to generating composites, the user can perform correlation
analyses of the CCM3 response to various SST forcings (e.g., Fig. 5.1) at http://www.esrl.noaa.gov/psd/Composites/CCM/Correlation/. Anticipated
changes in computing infrastructure will permit an increasingly larger
volume of climate model data to be made available on-line, and it is
likely that CDC will increasingly host model data to support climate
assessment research.